1. Field of the Invention
This invention relates to an apparatus for optically recording and reproducing information, and more particularly to an apparatus for recording and reproducing information such as video and audio signals in the form of concentric circles or in the form of a spiral on a recording medium having, for example, a planar recording surface by a light beam or recording and reproducing information on a medium such as a magnetic tape or the like by a light beam.
2. Description of the Prior Art
Apparatuses for recording various types of information on a recording medium by the use of a light beam and reading out the recorded information by the use of a light beam are known. Among these apparatuses, there are ones in which a monitoring light beam is provided discretely from a recording light beam to confirm whether information has been accurately recorded on the medium and the recorded information is immediately reproduced by the monitoring beam. Optical information recording apparatuses in which such a monitoring light beam is provided are disclosed in Japanese Laid-open Patent Application No. 3405/1977, Japanese Laid-open Patent Application No. 48504/1978, Japanese Laid-open Patent Application No. 163531/1981 and Japanese Laid-open Patent Application No. 17546/1983.
Of these publications, Japanese Laid-open Patent Application No. 48504/1978 shows that the monitoring light beam is utilized also as a light beam for the focus control during recording. Also, Japanese Laid-open Patent Application No. 17546/1983 shows that a part of the monitoring light beam is divided and tracking is effected by the divided light beam.
However, in the prior art, it has been only during recording that both of the recording light beam and the monitoring light beam are used and, as shown in Japanese Laid-open Patent Application No. 17546/1983, for example, it has been usual that during reproduction, the recording light source is not turned on and the recording light beam is not utilized. Accordingly, for example, in the case of Japanese Laid-open Patent Application No. 17546/1983, during reproduction, the focus control and the tracking control must be effected only by the monitoring light beam, and this has led to the cumbersomeness of the adjustment of the respective control systems and the problem of the crosstalk or the like between the focus control signal and the tracking control signal in the detecting system.